This invention relates generally to material handling and more particularly, to an improved part transfer apparatus.
Ongoing efforts to increase the efficiency and output of production operations have resulted in a continuing focus on how materials are moved with respect to the operations being performed. Often part processing machines and stations are separated by significant distances, and parts being processed are moved on conveyors between the processing machines and stations. In an effort to optimize the utilization of floor space, processing machines and stations are being moved into closer proximity. Generally each machine or processing station has a dedicated material handling device that loads the machine or station by picking up a part from an input position and thereafter, unloads the machine or station by depositing the part at a discharge position. The input and discharge positions are often the same position.
Thus, as one machine or station is brought into proximity with another machine or station, the parts must be transferred from the discharge position of one machine or station to the load position of the other machine or station. The path of the part transfer may require only a horizontal transfer of the parts, or the transfer may require that the parts be moved along horizontal and vertical paths. Further, the machines may be in such close proximity that a conveyor device is too large; and therefore, other material handling devices must be considered.
There are many commercially available devices for transferring a part from one location to another. For example, linear slides are commercially available which utilize a pneumatic cylinder to provide relative linear motion between the cylinder body and a cylinder piston or rod. Often, two cylinder rods or a noncylindrical cylinder rod are used so that there is no relative rotation between the cylinder body and rods, and the cylinder provides a stable support under load. While the commercially available units are useful in a great many applications, the commercially available units have several limitations. For example, when moving parts between stations located at opposite ends of the cylinder stroke, it is often necessary for the part to be accurately placed with respect to each of the stations. While many cylinders have the ability to finely adjust the end position at one end of the stroke, such cylinders do not provide the capability of finely adjusting the end position at the other end of the stroke. One can attempt to adjust the mounting location of the cylinder to achieve that purpose, however such an adjustment is coarse and difficult to use with any degree of precision.
Generally commercially available cylinders have only a relatively small block that moves between the ends of the stroke. Further, the block generally has no significant dimension in the direction of part motion, and therefore, if multiple parts are to be used or part detectors are to be used, special tooling must be designed for the moving block which substantially increases the cost, size and weight of the part transfer device. In addition, often it is required that a horizontal cylinder be attached to an elevator device such as a vertical cylinder. Therefore, the weight of the cylinder assembly is important, and any increase in the weight of the whole cylinder unit adversely impacts the design of the elevator unit. It is also important that the cylinder unit be kept as small as possible. As processing stations are brought closer together, any auxiliary equipment must kept to a minimal size, so that there is minimal interference in the space between machines. Such space is required for machine maintenance and therefore, must remain minimally obstructed, or such obstructions must be designed so that they can be readily moved to a noninterfering location.
Consequently, there is a need for a part transfer device that does not have the limitations and disadvantages of known devices for transferring parts from one location to another.